A friend tells me dolphins are whales. I think dolphins and whales are both
mammals but not the same thing. Which of us is right?

Dear Thera ,

Your friend is correct but , you are not completely incorrect. Dolphins are
indeed smaller whales.
However common parlance does use the word whale for the larger species. The
confusion arises
due to the way the word whale is commonly used. The more accurate term is
cetacean.